Sectional overhead doors have long been employed in both residential structures and commercial and industrial buildings. Such sectional overhead doors are normally designed not only to protect a garage or commercial establishment from the elements, such as rain, snow, wind, and temperature extremes, but also to provide security for a residence or commercial establishment. In this respect, sectional doors are virtually universally provided locking systems so that when such a door is in the closed position, it may be locked to prevent the entry or departure of unauthorized persons.
In the past, the locking systems for sectional overhead doors have primarily involved two types of systems, i.e., manual and motorized. For the most part, manual systems are employed when the sectional overhead door is not controlled by a powered or motorized operator. Such locking systems have effected the locking function in a number of different ways. In general, manual locking systems are normally activated by a handle mounted on the exterior surface of the door, often with redundant handles on the interior surface of the door that activate sliding bars, cables, or the like, which interact with either the track system for the door or a specially configured strike, which is attached to the doorjambs, commonly proximate to the track system for the door. These locking systems normally employ levers that attach to a lock disk, which is manually rotatably actuated to effect the locking and unlocking functions. In many instances, a lock mechanism has been incorporated or positioned in operative relation to the lock handle or lock disk, such as to preclude actuation of the lock system in the locked position without a key or other entry device. In some instances, these locking systems have been spring loaded so that the door locks automatically when closed and can be unlocked manually. These conventional locking systems have been commonly known for many years and employ a variety of bars, rods, and the like, together with associated mounting hardware, to carry out the desired locking function, usually at both ends of the sectional overhead door. Most of these prior-art manual systems require numerous additional hardware components, such as handles, lock disks, lock bars, strikes, catches, and other components, which add substantial expense, increase the weight of the door, require installation and adjustment on site, and, as a result, are necessarily relatively expensive.
Variations of these conventional manual locking systems include locks that are positioned at the top of the door for manual actuation to move a stop or roller out of alignment with the top of a door to effect unlocking. In some instances, solenoid actuated locks have been employed to actuate various locking devices in lieu of a handle attached to the door requiring manual actuation. In other instances, actuating devices for doors, such as cables leading to displaced locations, may interface with a locking device, such that when the manually operated cable controlling the raising and lowering of the door is actuated, the locking device is deactivated to permit the door to raise or lower. Any security features in systems of this nature require the utilization of a separate locking system in conjunction with the handle for actuating the cable operator.
The second type of locking system, which has become increasingly employed in recent years, contemplates that the door be rigidly or otherwise interconnected with a motorized operator that effects the raising and lowering of the door. The most common of the motorized operator locking systems employ a draw bar or arms that interconnect a location on the top section of the sectional overhead door and a motorized screw or chain drive system that is fixedly mounted above the door. In systems of this type, the chain or drive screw is driven to a position, such that the draw bar or arms are preferably in proximity to and aligned with the plane of the door when the door is in the closed position. In this manner, any attempt to raise the door from the closed position is blocked by the rail of the operator housing the screw or chain, which is located above and perpendicular to the plane of the door.
Another type of motorized operator uses a closed loop system wherein there are pulleys and cables that both pull-up and pull-down of the door to effect its closing and opening motions. Other operator systems have proposed the usage of motor-driven gears on the door edges that engage a slotted track system to effect opening and closing of the door and require actuation of the drive system to move the door from the closed position. While each of these motorized systems may provide security features, none have achieved wide acceptance in the industry due to the complexity, cost, and other factors.